Here is the full list of all 19 Sproggiwood achievements.
Beat the game on Savage with every class.
Beat Uppmas Point on Savage with every class.
Beat the Floating Isles on Savage with every class.
Defeat Surma on Normal.
Defeat Surma on Easy.
Beat Ensi on Savage with every class.
Beat Ignis Caverna on Savage with every class.
Beat Hakkipunki on Savage with every class.
Kill 10 enemies in one turn.
Beat the Bloated Grotto on Savage with every class.
Beat Big Tree on Savage with every class.
Beat Goaturku on Savage with every class.
Beat Ickykolo on Savage with every class.
Kill a bizarro cloghead.
Kill 5 enemies in one turn.
Beat a dungeon without killing any enemies besides the boss.
Kill a monster that loves you.
Defeat Big Ick on Easy.
Defeat Big Ick on Normal.